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arXiv · 1908.00608

Quasi-Two-Dimensional Magnon Identification in Antiferromagnetic FePS3 via Magneto-Raman Spectroscopy

Amber McCreary·Jeffrey R. Simpson·Thuc T. Mai·Robert D. McMichael·Jason E. Douglas·Nicholas Butch·Cindi Dennis·Rolando Valdes Aguilar·Angela R. Hight Walker
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Abstract

Recently it was discovered that van der Waals-bonded magnetic materials retain long range magnetic ordering down to a single layer, opening many avenues in fundamental physics and potential applications of these fascinating materials. One such material is FePS3, a large spin (S=2) Mott insulator where the Fe atoms form a honeycomb lattice. In the bulk, FePS3 has been shown to be a quasi-two-dimensional-Ising antiferromagnet, with additional features in the Raman spectra emerging below the Neel temperature of approximately 120 K. Using magneto-Raman spectroscopy as an optical probe of magnetic structure, we show that one of these Raman-active modes in the magnetically ordered state is actually a magnon with a frequency of of approximately 3.7 THz (122 cm-1). Contrary to previous work, which interpreted this feature as a phonon, our Raman data shows the expected frequency shifting and splitting of the magnon as a function of temperature and magnetic field, respectively, where we determine the g-factor to be approximately 2. In addition, the symmetry behavior of the magnon is studied by polarization-dependent Raman spectroscopy and explained using the magnetic point group of FePS3.

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Amber McCreary, Jeffrey R. Simpson, Thuc T. Mai, Robert D. McMichael, Jason E. Douglas, Nicholas Butch, Cindi Dennis, Rolando Valdes Aguilar, Angela R. Hight Walker. 2019-08-01. Quasi-Two-Dimensional Magnon Identification in Antiferromagnetic FePS3 via Magneto-Raman Spectroscopy. https://doi.org/10.1103/physrevb.101.064416

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